Question

我有一个关于使用sql语句在表中组合两行的MySQL语句的查询。最初，我已经实现了代码，以在数据网格视图中显示员工的转变。

LocationName | StationName | 12:00 - 13:00 | 13:00 - 14:00 | 14:00 - 15:00
T2           | Counter     | Michael Joyce | Michael Joyce | Michael Joyce

如您所见，同一地点和车站下有两名员工。下一步，我将使用SQL语句键入格式，并最终使用SQL语句来报告查看器。

这是我试图以与上面显示的格式相同的SQL语句。

select
  z.LocationName,
  z.StationName,
  a.12001300,
  b.13001400,
  c.14001500
from (SELECT DISTINCT
        LocationName,
        StationName
      FROM satsschema.employeeslot
      where AllocationDate = '10-Aug'
          and LocationName = 'T2 PML'
          and StationName is not null) z
  left outer join (SELECT
                     LocationName,
                     StationName,
                     EmpName         AS '12001300'
                   FROM satsschema.employeeslot
                   WHERE Assigned = true
                       and AllocationDate = '10-Aug'
                       and (EmpTime = '12:00:00' && EmpTime < '13:00:00')) a
    on z.LocationName = a.LocationName
      and z.StationName = a.StationName
  left outer join (SELECT
                     LocationName,
                     StationName,
                     EmpName         AS '13001400'
                   FROM satsschema.employeeslot
                   WHERE Assigned = true
                       and AllocationDate = '10-Aug'
                       and (EmpTime = '13:00:00' && EmpTime < '14:00:00')) b
    on a.LocationName = b.LocationName
      and a.StationName = b.StationName
  left outer join (SELECT
                     LocationName,
                     StationName,
                     EmpName         AS '14001500'
                   FROM satsschema.employeeslot
                   WHERE Assigned = true
                       and AllocationDate = '10-Aug'
                       and (EmpTime = '14:00:00' && EmpTime < '15:00:00')) c
    on b.LocationName = c.LocationName
      and b.StationName = c.StationName

上面显示的这个SQL语句显示以下结果与我想要的不匹配。它显示如下：

LocationName | StationName | 12:00 - 13:00 | 13:00 - 14:00 | 14:00 - 15:00
T2           | Counter     | Michael       | Michael       | Michael

如您所见，它仅显示位置和工作站中的一名员工。如果在位置和工作站内有多个人，我还可以看到其他员工的SQL语句怎么办？有什么意见吗？

Answer 1

使用GROUP_CONCAT。见Can I concatenate multiple MySQL rows into one field?

有些事情：

SELECT z.LocationName, z.StationName, Block12.EmpList, Block13.EmpList, Block14.EmpList
FROM satsschema.employeeslot z
LEFT OUTER JOIN
(
    SELECT LocationName, StationName, GROUP_CONCAT(EmpName) AS EmpList
    FROM satsschema.employeeslot
    WHERE Assigned = true
        AND AllocationDate = '10-Aug'
        AND (EmpTime = '12:00:00' && EmpTime < '13:00:00')
    GROUP BY LocationName, StationName
) Block12
ON z.LocationName = Block12.LocationName
    AND z.StationName = Block12.StationName
LEFT OUTER JOIN
(
    SELECT LocationName, StationName, GROUP_CONCAT(EmpName) AS EmpList
    FROM satsschema.employeeslot
    WHERE Assigned = true
        AND AllocationDate = '10-Aug'
        AND (EmpTime = '13:00:00' && EmpTime < '14:00:00')
    GROUP BY LocationName, StationName
) Block13
ON z.LocationName = Block13.LocationName
    AND z.StationName = Block13.StationName
LEFT OUTER JOIN
(
    SELECT LocationName, StationName, GROUP_CONCAT(EmpName) AS EmpList
    FROM satsschema.employeeslot
    WHERE Assigned = true
        AND AllocationDate = '10-Aug'
        AND (EmpTime = '14:00:00' && EmpTime < '15:00:00')
    GROUP BY LocationName, StationName
) Block14
ON z.LocationName = Block14.LocationName
    AND z.StationName = Block14.StationName
WHERE AllocationDate = '10-Aug'
GROUP BY z.LocationName, z.StationName

使用sql语句组合两行

1 个答案: